Automatic control device for road graders and the like



T. RIVINIUS Feb. 14, 1967 AUTOMATIC CONTROL DEVICE FOR ROAD GRADERS ANDTHE LIKE Filed April 27, 1964 5 Sheets-Sheet 1 INVENTOR 77/600026mil/All;

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T. RIVINIUS Feb. 14, 1967 AUTOMATIC CONTROL DEVICE FOR ROAD GRADERS ANDTHE LIKE 5 Sheets-Sheet 2 Filed April 27, 1964 INVENTOR. filaboxzP/VM/ll/s Feb. 14, 1967 r. mvmlus 3,303,589

AUTOMATIC CONTROL DEVICE FOR ROAD GRADERS AND THE LIKE Filed April 27,1964 5 Sheets-Sheet 4 INVENTOR. m 73 200026 Flu M10: Y

1 I 9 \0 Q z/am Feb. 14, 1967 T. RlVlNlUS 3,303,589

AUTOMATIC CONTROL DEVICE FOR ROAD GRADERS AND THE LIKE Filed April 27,1964 5 Sheets-Sheet 5 United States Iatent O 3,303,5s9 AUTQMATIC CONTROLDEVICE FQR ROAD GRADERS AND THE LIKE Theodore Rivinius, 1011 Ave. B W.,Bismarck, N. Dak. 58501 Filed Apr. 27, 1964, Ser. No. 362,740 18 Claims.(Cl. 37-156) This is a continuation-in-part of my successively mutually, co-pending applications for Automatic Control Device, Serial No.154,288, originally filed November 22, 1961, now abandoned; Serial No.223,290, filed Septemher 7, 1962, now abandoned; and Serial No. 270,473,filed April 3, 1963, co-pending at the time of the filing of thispresent application.

The present invention has relation to an automatic control device forroad graders and the like and more particularly to a device which, whenattached to certain controls of a road grader or other earth workingmachine, will automatically maintain the earth working blade of such amachine at a selectively predetermined slope with respect to thehorizontal.

In a device made according to the present invention, a horizon sensingcase or pendulum case is mounted with respect to a frame member carryingthe earth working blade in such a manner that the angular relationshipbetween the vertical axis of the horizon sensing case with respect to aplane parallel with the longitudinal axis of the road grader andencompassing the lower working edge of the earth working blade can beselectively varied at will. A pendulum is pivotally mounted in thehorizon sensing or pendulum case in operational alignment with a pair ofswitches in said case, the arrangement being such that the pendulum willalways tend to move toward vertical alignment and one or the other ofthe switches being activated to closed or on position by the pendulumwhenever it is not in vertical alignment. These switches when closed oron activate first and second control circuits, respectively. Each ofthese circuits, when thus activated, operate on the normal controls ofthe grader or the like to tend to move the earth working blade indirection to cause its respective closed switch to move out of contactwith the pendulum and hence to an open or off position.

Road graders typical of the devices on which the apparatus of thepresent invention will prove useful can include a circle frame or thelike to which the earth working blade is fixedly mounted. Such a circleframe will lie in a plane parallel to the lower working edge of theearth working blade. This circle frame can typically be mounted on adraw bar linkage which is pivotally mounted at a forward end thereof tothe main frame of the grader.-

By rotating the circle frame about its axis, the angular relationship ofthe earth working blade with respect to the longitudinal axis of themain frame of the grader can be changed as desired. Assuming that theslope of the area which is to be graded is other than horizontal, thenthe plane of the circle frame can not be horizontal either. As thecircle frame is rotated to change the angle of attack of the earthworking blade, the angle of the plane of the circle frame will have tobe changed in order to maintain the lower edge of the earth workingblade in the desired plane. To accomplish this, an upright support plateis pivotally mounted on an upright support axis to a main mountingbracket reference arm in such a manner that the upright support axis ismaintained at all times in parallel relationship to the axis of thecircle frame and perpendicular to the longitudinal axis of the machine.The horizon sensing case is then supported in fixed angular relationshipto the upright support plate so that any deviation from the preselectedangle by the plane of the circle frame and the corresponding 3,363,589Patented Fete. 14, 1957 upright support axis as the circle frame isrotated will institute a corrective signal within the sensing case toreturn these parts to the preselected angle.

The horizon sensing case is pivotally mounted to the upright supportplate on an axis aligned with the longitudinal axis of the machine. Theangular relationship of this case to the support plate is controlled bya motor mounted on the draw bar linkage, and by controlling thisrelationship, the slope being formed by the earth working blade withrespect to the horizontal is controlled.

The control circuits and the controls operated by those circuits can besimple on-off arrangements whereby the angle of the earth working bladecan be continuously changed until the corresponding switch in thependulum case goes to the off condition. Such arrangements have beensatisfactorily used. Hydraulic valving is particularly adaptable to thiskind of usage. However, changes in the ambient temperature can effectthe flow properties of the hydraulic fluids involved, and this factorand other factors can result in sluggish operation of the controls or ina hunting operation whereby the machine is overcontrolled so that theearth working blade goes too far, thus causing the opposite switch to beactivated and an opposite correction to be called for.

It has been found that these difiiculties can be overcome by providingthat the control circuitry and controls, while a particular switch is inthe activated or on condition, operate intermittently to causecorrections to the circle frame plane angle in small increments. Suchcontrols can be either hydraulic or electrical, but electrical controlsare particularly effective when used in this manner.

In the drawings,

FIG. 1 is a side elevational view of a road grader having a controldevice made according to the present invention installed thereon;

FIG. 2 is an enlarged fragmentary perspective view of certain ofessential elements of the grader and of the grader control of theinvention as seen from above the right rear quadrant of the grader;

FIG. 3 is an enlarged horizontal sectional view taken on the line 33 inFIG. 1;

FIG. 4 is an enlarged vertical sectional view taken on line 44 in FIG.3;

FIG. 5 is a vertical sectional view taken on the line 5-5 in FIG. 4;

FIG. 6 is a greatly enlarged fragmentary perspective view of certain ofthe elements of FIG. 2 as seen from above the right front quadrant ofthe machine; and

FIG. 7 is a schematic representation of the control circuitry of thisform of the invention.

A road grader 15, which is conventionally made, includes an elongatedmain frame 16 and is mounted on a plurality of wheels 17. The grader ispowered with an engine 18 through suitable mechanism (not shown). A cab19 is positioned on the main frame of the grader and houses the gradercontrols indicated generally at 20.

An earth working grader blade 21 is mounted through suitable brackets 22to a circle frame 23. The circle frame is rigidly attached to an A-frameor draw bar linkage 26 which in turn is pivotally connected to the mainframe 16 of the grader as at 177 in any usual or preferred manner. Theearth working blade 21 may be rotated with the circle frame 23 about theaxis 25 of the circle frame. In this way, the blade can be angled to anydesired position.

The depth of the earth working blade 21 is controlled throughconventional power lift mechanism (not shown) mounted in a housing 24.The mechanism drives a pair of rock shafts 27 which are each rotatablymounted on suitable support bearings 28 attached to main frame 16. Eachrock shaft 27 has a lever 29 fixedly attached thereto. A link 34) ispivotally mounted as at 31 to each of the levers 29 and extendsdownwardly to engage at 31a a bracket 32 which rotat-ably supports thecircle frame and forms a part of the A-frame 26.

A first rock shaft control lever or handle 33 is pivotally mounted as at35 to housing 24 and operates a control rod 36 which operates mechanismto control the rotational position of left rock shaft 27 and itsattached lever 29. A second rock shaft control lever or handle 34 ispivotally mounted as at 37 to housing 24 and operates a control rod 38which operates mechanism to control the rotational position of rightrock shaft 27 and its attached lever 29. See FIGS. 1 and 2. Each lever29, acting through its associated link 30, will raise or lower one sideof the bracket 32 and the circle frame and consequently raise or lowerone end of the grader blade 21. Other grader control levers are providedfor the other grader operations.

The structure just described is conventional and is used on a largenumber of road graders commercially available at the present time.

An automatic control device made according to the present inventionincludes a horizon sensing unit 40 which has a main mounting bracket orreference arm 42 ivotally mounted on a cross beam 41. This cross beam 41is fixedly attached between the two legs of the A-frame linkage 26. Thuswhen the plane of the circle frame and consequently of the A-framelinkage 26 is inclined from the horizontal, the cross member 41 andmounting bracket 42 are also inclined from the horizontal.

The sensing units 40 also includes a pendulum case or horizon sensingcase 43 having an integral case pivot pin 44 extending outwardlytherefrom.

The main mounting bracket 42 is generally U-shaped in configuration andincludes a generally fiat bracket plate 47, an arm portion 48 integralwith and extending at right angles from the bracket plate 47, and an armextension 49 integral with said arm portion at an end thereof oppositesaid plate and extending outwardly from said arm in generally parallelspaced relationship to the bracket plate 47. The bracket plate 47 ispivotally connected to the cross beam 41 by means of a bracket platemounting pin integral with said plate.

The arm extension 49 is in two parts and includes matching face plates151 and 152 which are fastened to each other through the instrumentalityof bolts 153. The face plate 152 is provided with elongated arcuateslots 154 to provide for limited rotatable adjustment of the face plateswith respect to each other. The outer end of the extension arm 49 of themain mounting bracket 42 includes an integral reference collar orbearing 155 having an axis lying in a generally vertical direction.

As perhaps best seen in FIG. 6, the circle frame 23 is provided with apair of reference rod support brackets 156 and 157 which are welded tothe circle frame and extend downwardly in clearing relationship to thebull gear flange portion of that frame to terminate in upwardlyextending rod supporting end portions 158. These reference rod supportbrackets 156 and 157 are mounted on diametrically opposite sides of thecircle frame 23 along a diameter of that frame which has been designatedby the broken line 159. The plane of the circle frame is defined byincluding this diameter line 159 and a second diameter line 170 whichalso lies in a vertical plane parallel with the longitudinal axis of themain frame of the grader. These diameter lines intersect at the center160 of the circle frame, and a line perpendicular to the plane of thecircle frame and forming the axis of the frame has been previouslydesignated 25. A circle frame axis reference rod 161 is fixedly mountedin each of the rod supporting end portions 158. This rod 161 has anupwardly extending circle frame axis locating stud 162 integrallyextending in upward direction, and the reference rod 161 is carefullyadjusted and fastened as at 163 to the support bracket end portions 158to position this axis locating stud to be exactly concentric with thecircle frame axis line 25.

With the stud 162 rotatably mounted inside of the reference collar 155of the main mounting bracket 42, and with the bracket plate mounting pinpivotally mounted in the cross beam 41 to lie on the longitudinallyextending diameter line 170, any change in the angle of the circle frameplane, and consequently in the circle frame axis 25, will be reflectedexactly by a change in the position of the bracket plate 47.

A pair of main bracket mounting ears 166 and 167 are integral with thebracket plate 47 and have cylindrical openings therethrough having acommon upright support axis parallel with circle frame axis line 25 andpassing through longitudinally extending diameter line 170. A generallyupright support plate 172 has upright support plate ears 173 and 174integral therewith and extending outwardly therefrom. The support plate72 and the bracket plate 47 are mounted in pivotal relationship to eachother by a pintle pin 175 extending through bracket mounting ears 166and 167 and support plate ears 173 and 174 on the upright support axis.The previously mentioned case pivot pin 44 is pivotally mounted to thesupport late 172 on an axis lying in the vertical plane defined by thecross beam axis line 25 and the diameter line 170.

The circle frame 23 includes an'outer slider 179 which is slidablysupported in tracks or slides 178 extending outwardly from and formingpart of the A-frame bracket 32 in any conventional or desired manner.The earth working grader blade mounting brackets 22 are attached to thisslider 179, and as it rotates with respect to the A-frame and the slides178, the blade 21 will also rotate about the axis 25 of the circle frame23. As seen in FIGS. 2, 3 and 6, the inner peripheral edges of theslider 179 have gear teeth and form what is commonly called a bull gear.These gear teeth are used to rotate the circle frame slider about itstracks or slides 178 through the use of a suitable gear driven from agear housing 181. This gear housing is power driven through conventionalmechanism (not shown). Thus the earth working blade 21 can be moved toany desired transverse angle with respect to the longitudinal axis ofthe grader. A lower working edge 100 of the earth working grader blade21 will define the work plane of the earth being graded as the gradermoves in the direction of the longitudinal axis of the main frame 16 andin the direction of a vertical plane passing through the circle framediameter line 170. This work plane will be precisely parallel with theplane of the circle frame as defined by the diameter lines 170 and 159.By accurately controlling this circle frame plane, the work plane iscontrolled.

As the gear teeth of the circle frame and the gear in the gear housing181 are utilized to rotate the circle frame thus changing the' angularrelationship of the diameter line 159 to the diameter line 170; in everycase except where the working edge 16!) is horizontal, the plane of thecircle frame will change. Unless the linkages 30 and the associated.power mechanism are used to correct this change to restore the sameplane, the work plane will deviate from that desired. The parallelrelationship of the axis of the reference collar to the upright supportaxis of the main bracket mounting ears 166 and 167 automaticallyaccomplishes this correction.

As perhaps best seen in FIGS. 4 and 6, inside of the pendulum case orhorizon sensing case 43, a pendulum 50 is mounted on a pendulum shaft 51which in turn is rotatably mounted on suitable bearings 52, 52 in thecase 43. The bearings 52, 52 are anti-friction bearings and permit theshaft 51 to rotate very easily. The pendulum 50 is mounted for movementabout the longitudinal axis of the shaft 51 but is restrained frommovement longitudinally along the shaft. The pendulum has a pair ofintegral vanes 53, 53 positioned on opposite sides thereof. These vanesare spaced very slightly inwardly from the corresponding side edges ofthe case 43. Two other side surfaces 54, 54 of the pendulum are spacedinwardly a relatively greater distance from their corresponding sideedges of the case 43. This is to allow the pendulum to move from side toside within the pendulum case as it pivots about the axis of the shaft51. A pair of stop bolts 55, 55 are threadably mounted as at 56 withrespect to the side edges of the pendulum case 43. The bolts are alignedwith side surfaces 54, 54 of the pendulum and are adapted to engagethese side surfaces to prevent the pendulum from swinging farther thannecessary to operate the control system. The pendulum case 43 is filledwith a highly refined oil, indicated at 57, which dampens the movementof the pendulum as it swings about the axis of shaft 51. The smallclearance between vanes 53 and the corresponding sides of the pendulumcase is to constrict the flow of oil as the pendulum swings.

The tilting of the case 43 about its pivot pin 44 is controlled throughthe linkage 60 which is pivoted to the case 43 as at 135. The operationof this linkage and the manner in which it fixes the angularrelationship of the horizon sensing pendulum case 43 with respect to theupright support plate 172 will be explained more fully later.

Pendulum shaft 51 has an end portion 61 which extends outwardly from thecase 43 into a housing 59 which is integral with the case. An actuatinglug or ear 62 is fixedly attached to the shaft end portion 61. As bestseen in FIG. 5, a first switch 63 is mounted on housing 59 on one sideof the lug 62 and a second switch 64 is mounted on the housing on theopposite side of the lug 62. Actuating buttons65, 65 of the switches arepositioned adjacent the lug.

As seen in FIG. 7, a flasher 102 is connected from a source ofelectromotive force 73 through each of the switches 63 and 64 to areversing switch 103. This reversing switch can be a three-positionswitch in which the center or disconnect position can serve as the offswitch for the control apparatus. A separate power off and on switch 104can be also utilized if desired.

When reversing switch 103 is thrown to the upward position as seen inFIG. 7, the power will flow through the flasher and switch 63 (whenclosed) to a relay 105 which will cause a first solenoid 106 to heenergized. Power will flow through the flasher and switch 64 (whenclosed) to a relay 107 which will power a second solenoid 108. With thereversing switch in this upward position, tilting of the pendulum caseto cause the lug 62 to close switch 64 will cause the second solenoid108 to be energized intermittently every time the flasher permits theflow of power therethrough, and solenoid armature 109 will be moved tothe left as seen in FIG. 7. Solenoid operating arm 110, integral withthe armature 109, will also move to the left. When the flasher is notpassing current, the springs 111 and 112 will center the armature to theposition as seen in FIG. 7.

When the case moves so that the lug 62, under the urging of the pendulum50, closes switch 63, current through the flasher 102 will cause currentto flow through the first solenoid 106, and the solenoid arm 110 andarmature 109 will move to the right as seen in FIG. 7. When currentstops flowing through the flasher, the springs will again center thearmature.

The action described above results in a series of intermittentincremental movements of the armature arm 110 in direction determined bythe positioning of the reversing switch 103 and by the relationship ofthe pendulum 50 and lug 62 with respect to the horizon sensing case 43and the switches mounted with respect thereto.

The solenoid mechanism may be enclosed in a solenoid box 113 as seen inFIG. 2, and the controls for utilizing the intermittent forward orreverse thrusts of the solenoid arm 110 include a control shaft 115fixedly mounted in the cab 19 on upstanding bearing lates 116. First andsecond rock shaft control arms 123 and 124, respectively, are freelypivotally mounted on a control shaft and a pair of rock shaft controllinkages 125 and 126 pivotally connect these arms and their respectivefirst and second rock shaft control levers 33 and 34. A control tube 117is freely rotatably mounted on the control shaft and is slidablelongitudinally along it. A solenoid contlrlolled arm 118 is pivotallymounted to the solenoid operating arm 110 and is keyed to the controltube 117 to be able to cause it to rotate, but to be freely slidablelongitudinally with respect to it. Clutch dogs 119 and 120 are fixedlypositioned on opposite ends of the control tube 117, and apertures areprovided in each of the first and second rocker shaft control arms 123and 124 for receiving their respective clutch dogs when the control tubeis slid -by a shifting mechanism '131 toward that particular controlarm. The shifting mechanism 131 is a manually operable lever attached tothe control tube with a suitable collar.

The parts are positioned in FIG. 2 with the dogs out of engagement forpurposes of clarity; 'but it will be understood that with the clutch dog119 in locked relationship with respect to the first rock shaft controlarm 123, movement of the solenoid operating arm 110 away from thesolenoid box 113 will cause the first rock shaft control lever or handle33 to be moved back toward the machine operator to the end that rockshaft control rod 36 activates its rock shaft to result in a change inthe horizontal positioning of its corresponding link 30 with aconsequent change in the angular relationship of the circle frame planeand consequently thework plane as determined by the loci of movement oflower working edge 100 of the greater blade 21. Since the solenoidoperating arm 110 is only in the activated position momentarily whilethe flasher is passing current, the increment of angular displacement ofthe operating plane will be slight. If the incremental movement is notsufficient to cause the lug 62 to move into clearing relationship withrespect to the closed switch which originally triggered the movement,then when next the flasher fires, a further incremental movement in thesame direction will take place. As soon as a particular small movementis sufiicient to cause the switch 63 or 64 to move to the opencondition, no such further control movements.

will be forthcoming.

Should the grader operator want the earth working grader blade 21 tomake a deeper or shallower cut while the clutch dog 119 is keying theangular movement of the control tube 117 to that of the first rock shaftcontrol arm 123, he has merely to operate the second rock shaft controlhandle 34 to cause the right side of the A-frame 26 and circle frame 23to be raised or lowered as desired. As the pendulum attempts to maintainits vertical relationship, it will activate one of the switches 63 or64, and the automatic control mechanism just described will operate toraise or lower the left side of the A-frame and circle frame to maintainor re-establish the desired work plane.

A main object of the invention is to permit the ready establishment ofany desired work plane with respect to the horizontal, and to maintainthat plane while operating the grader. Since the upright support axis ofthe pintle 175 is always in exact perpendicular relationship to the workplane as defined by the loci of the lower working edge 100 of the earthworking blade 21 as it moves in the direction of the longitudinal axisof the grader, it is necessary only to establish the angularrelationship" of the horizontal sensing case with respect to the uprightsupport plate 172 and the upright support axis which is fixed withrespect to that plate. This is done by utilizing the connection at 135between the linkage 60 and the top portion of the case 43. A reversiblemotor 121 operating through a suitable gearing 122 moves the link 60longitudinally of its own axis to rotate the case 43 about its pivot pin44.

In order to indicate the extent of the rotation of the case 43 withrespect to the support plate 172, and consequently the angularrelationship of the work plane of the grader to the horizontal, agenerally rectangular indicia frame 74 of tubular material is fixedlymounted r 7 through the instrumentality of U-sh aped arm 75 to the topof the upright support-plate 172. An indicia plate 76 is calibrated indegree-s or in slope and is fixedly positioned at the top of the indiciaframe 74. An indicator cable 77 is fixedly mounted with respect toopposite sides of the top of the case 43 by an indicator cable mountingbracket 78 and extends into the tubular material of the indicia frame74, up through and clear around the frame. The underside of the tubularmaterial of the indicia frame is open along the top edge thereof toallow an indicator needle 79, attached to the indicator cable 77, toextend under the indicia plate 76 and up in front of it to positionwhere the relative angular positioning of the case 43 with respect tothe support plate and consequently with respect to the work plane of thegrader can be indicated.

In order to maintain the pendulum axle 51 in exact alignment with thelongitudinal axis of the grader, it is necessary that the plane of theupright support plate 172 be maintained in perpendicular relationship tothis longitudinal axis. This is accomplished by the use of astiff-legged tie bar linkage 80 which is pivotally mounted through adouble pivot joint 81 to a forward portion of the main frame 16 and ispivotally mounted as at 82'to U-shaped arm 75 at position offset fromthe center of the grader.

The circuit for operating the reversible motor 121 is seen in FIG. 7,wherein a second reversible switch 38 will be normally positioned in theneutral or off condition and can be manually manipulated to cause themotor to run frontward or backward, thus to adjust the angularrelationship of the case 43 to the desired work plane. The angularrelationship of the case to the circle frame plane will be indicated bythe indicator needle 79, which the operator will watch as he operatesmotor 121. As soon as the automatic controls are activated, the deviceof the invention will conform to the work plane of the grader to thatindicated on the indicia plate by the indicator needle.

Various flasher operation rates can be used to accomplish the purposesof the invention, but in one particular set of circumstances, a flasherfiring rate of 90 times per minute has been found to be mostsatisfactory.

What is claimed is:

1. The combination with a motor grader having a wheel mounted mainframe, said main frame having an elon gated longitudinal axis, a drawbar linkage pivotally mounted at a forward end portion thereof to aforward end portion of said main frame, said draw bar linkage defining adraw bar plane and having an elongated longitudinal axis, a circle framedefining a circle frame plane and mounted on a rear end portion of saiddraw bar linkage to be rotatable about its own circle frame axis and ,7

to maintain a fixed angular relationship between said draw bar plane andsaid circle frame plane, a generally transversely positioned earthworking blade fixedly mounted with respect to said circle frame, andpower means to selectively raise and lower one end portion of said bladewith respect to the other as the angle of the'circle frame plane ischanged with respect toa horizontal plane, of: an automatic controldevice including a main mounting bracket pivotally mounted on thelongitudinal axis of said draw bar linkage, an upright support platepivotally mounted to said main mounting bracket on an upright supportaxis, means for maintaining said support axis in parallel relationshipto said circle frame axis, a horizon sensing case mounted on saidupright support plate and having a gravity responsive element pivotallymounted in said case on a generally horizontal pivot axis, switch meansin said case associated with said gravity responsive element to bedeactivated when said case and said element are in a normal verticallyaligned relationship to each other and to be activated when said caseand said element are in unaligned relationshipwith each other, andcontrol means operative upon activation of said switch means power meansto cause said power means to change the height of one end of said bladein a series of incremental steps.

3. The combination as specified in claim 1 wherein said means formaintaining said support axis in parallel relationship to said circleframe axis includes a circle frame axis locating stud, a circle frameaxis reference rod integral with said locating stud and fixedlypositioned with respect to said circle frame to locate said stud on saidcircle frame axis, a locating stud reference collar in concentricbearing relationship to said stud, and an extension arm integral withsaid main mounting bracket and said collar.

4. The combination as specified incl-aim 3 wherein said arm extension isin two parts, each part including a face plate in facing relationship tothe other part, and means for fastening said plates to each otherthrough out a limited range of angular displacements one from the other.

5. Thecombination as specified in claim 1, and meansfor varying theangular relationship of the horizon sensing case to the upright'supportaxis of the upright support plate.

6. The combination with a motor grader having a wheel mounted mainframe, said main frame having an elongated longitudinal axis, a draw barlinkage pivotally mounted at a forward end portion thereof to a forwardend portion of said main frame, said draw bar linkage defining a drawbar plane and having an elongated longitudinal axis, a circle framedefining a circle frame plane and mountedon a rear end portion of saiddraw bar link age to be rotatable about its own circlefr-ame axis and.to maintain a fixed angular relationship between said draw bar plane andsaid circle frame plane, a generally transversely positioned earthworking blade fixedly mounted with respect to said circle frame to havea lower working edge thereof lying at all times in a plane parallel tosaid circle frame plane, and power means to selectively raise and lowerone end portion of said blade with respect to the other as the angle ofthe circle frame plane is changed with respect to a horizontal plane,of: an automatic control. device including a main mounting bracketpivotally mountedon the longitudinal axis of said draw bar linkage whichaxis intersects said circle frame axis, an upright sup port platepivotally mounted to said mounting bracket on an upright support axiswhich intersects said longitudinal draw bar axis, means for maintainingsaid support axis in parallel relationship to said circle frame axis, ahorizon sensing case pivotally mounted on said upright support plate andhaving a gravity responsive element pivotally mounted in said case on agenerally horizontal pivot axis, means for maintaining said pivot axisin parallel relationship to the longitudinal axis of said main frame,switch means in said case associated with said gravity responsiveelement to be deactivated when said case and said element are in anormal vertically aligned relationship to each other and to be activatedwhen said case and said element are in unaligned relationship with eachother, and control means operative upon activation of said switch meansto cause said power means to change the height of at least one endportion of said blade to tend to bring said case and said element intonormal vertical alignment.

7. The combination as specified in claim 6 and means to adjust theangular relationship of said horizon sensing case with respect to theupright axis of the uprightsupport plate.

8. The combination as Specified in claim 7 wherein said means foradjusting said case include a link extending from said case to said drawbar frame and power means for selectively manipulating said link ineither lateral direction with respect to the longitudinal axis of thedraw bar linkage to cause said case to pivot with respect to saidupright support plate.

9. The combination as specified in claim 8, and means for visuallyindicating the angular relationship of said case to said upright plateaxis.

10. The combination as specified in claim 9 wherein said means forvisually indicating includes an indicia frame unit and an indicatorcable unit, one of said units being fixedly mounted with respect to aportion of said case spaced from its pivotal mounting point and theother of said units being fixedly mounted with respect to a portion ofsaid upright support plate spaced from said case pivotal mounting point,said indicator cable unit extending around a track provided by saidindicia frame, an indicia plate being mounted on said indicia frame, anindicator needle being fixedly attached to said indicator cable toextend to position in visual alignment with said indicator plate, andvisible indicia on said plate positioned contiguous to the variouspossible locations of said indicator needle.

11. The combination as specified in claim 10 wherein said means formaintaining said pivot axis in parallel relationship to the longitudinalaxis of said main frame includes a stiff tie bar linkage pivotallymounted to said main frame at a forward portion thereof and pivotallymounted with respect to said upright support plate at a point on saidplate spaced from the longitudinal axis of said main frame.

12. The combination as specified in claim 11 wherein said control meansincludes an electrical circuit means feeding intermittent electricalimpulses through said switch means when activated toelectromagnetic-mechanical transducers which are intermittentlyoperative on said power means to cause said power means to change theheight of one end of said blade in a series of incremental steps.

13. The combination as specified in claim 11 wherein said means formaintaining said support axis in parallel relationship to said circleframe axis includes a circle frame axis locating stud, a circle frameaxis reference rod integral with said locating stud and fixedlypositioned with respect to said circle frame to locate said stud on saidcircle frame axis, a locating stud reference collar in concentricbearing relationship to said stud, and an extension arm integral withsaid tmain mounting bracket and said collar.

14. The combination as specified in claim 13, and means for varying theangular relationship of the horizon sensing case to the upright supportaxis of the upright support plate.

15. In a road grader or the like having an earth working blade, powermeans operable to control the angular position of said blade withrespect to a horizontal plane, and an element for sensing therelationship of the cutting edge of the earth working blade with respectto a reference plane, the improvement comprising a control circuitoperable in response to said element and controlling said power means,and interrupter means in said control circuit to alternately disablesaid power means and permit said power means to operate when the controlcircuit is energized thereby giving a pulsating action to said powermeans.

16. The combination as specified in claim 15 wherein said controlcircuit is comprised as an electrical circuit, and said interruptermeans comprises a device which alternately makes and breaks saidelectrical circuit.

17. The combination with a motor grader having a wheel mounted mainframe, said main frame having an elongated longitudinal axis, a draw barlinkage pivotally mounted at a forward end portion thereof to theforward end portion of said main frame, a generally transverselypositioned earth working blade, means to mount the blade to said drawbar, and power means to selectively raise and lower one end portion ofsaid blade with respect to the other, of: an automatic control deviceincluding sensing means to sense a deviation of said blade from apreselected angle with respect to a horizontal plane, and control meansactivated by said sensing means to operate said power means in responseto deviation of said blade from the preselected angle, said controlmeans including an impulse producing unit which intermittentlyinterrupts operation of said power means to change the height of one endof said blade in a series of incremental steps, wherenever the sensingmeans indicates the blade has deviated from its preselected angle.

18. The combination as specified in claim 17 wherein said control meansincludes a solenoid means to operate said power means, an electricalcircuit to control said solenoid, said electrical circuit including afirst switch operated by said sensing means, and an interrupter switchin series with said first switch, said inter-nt-pter switch open ing andclosing at a preselected frequency.

References Cited by the Examiner UNITED STATES PATENTS 2,029,455 2/1936Wilson 37-156 2,636,290 4/1953 Bell 37156 2,904,911 9/1959 Colee 37-1562,941,319 6/1960 Beemer et a1 37156 2,961,783 11/1960 Bowen et a1 371563,094,796 6/1963 Atchley 37-156 ABRAHAM G. STONE, Primary Examiner.

R. L. HOLLISTER, Assistant Examiner.

15. IN A ROAD GRADE OR THE LIKE HAVING AN EARTH WORKING BLADE, POWER MEANS OPERABLE TO CONTROL THE ANGULAR POSITION OF SAID BLADE WITH RESPECT TO A HORIZONTAL PLANE, AND AN ELEMENT FOR SENSING THE RELATIONSHIP OF THE CUTTING EDGE OF THE EARTH WORKING BLADE WITH RESPECT TO A REFERENCE PLANE, THE IMPROVEMENT COMPRISING A CONTROL CIRCUIT OPERABLE IN RESPONSE TO SAID ELEMENT AND CONTROLLING SAID POWER MEANS, AND INTERRUPTER MEANS IN SAID CONTROL CIRCUIT TO ALTERNATELY DISABLE SAID POWER MEANS AND PERMIT SAID POWER MEANS TO OPERATE WHEN THE CONTROL CIRCUIT IS ENERGIZED THEREBY GIVING A PULSATING ACTION TO SAID POWER MEANS. 